Forms Of Tocopherols Research Articles

δ-Tocopherol Is More Active than α- or γ-Tocopherol in Inhibiting Lung Tumorigenesis In Vivo

In contrast to strong epidemiologic, preclinical, and secondary clinical evidence for vitamin E (tocopherols) in reducing cancer risk, large-scale clinical cancer-prevention trials of α-tocopherol have been negative. This vexing contrast helped spur substantial preclinical efforts to better understand and improve the antineoplastic activity of tocopherol through, for example, the study of different tocopherol forms. We previously showed that the γ-tocopherol-rich mixture (γ-TmT) effectively inhibited colon and lung carcinogenesis and the growth of transplanted lung-cancer cells in mice. We designed this study to determine the relative activities of different forms of tocopherol in a xenograft model, comparing the anticancer activities of δ-tocopherol with those of α- and γ-tocopherols. We subcutaneously injected human lung cancer H1299 cells into NCr nu/nu mice, which then received α-, γ-, or δ-tocopherol or γ-TmT in the diet (each at 0.17% and 0.3%) for 49 days. δ-Tocopherol inhibited tumor growth most strongly. γ-Tocopherol and γ-TmT (at 0.3%) also inhibited growth significantly, but α-tocopherol did not. δ-Tocopherol also effectively decreased oxidative DNA damage and nitrotyrosine formation and enhanced apoptosis in tumor cells; again, γ-tocopherol also was active in these regards but less so, and α-tocopherol was not. Each supplemented diet increased serum levels of its tocopherol - up to 45 μmol/L for α-tocopherol, 9.7 μmol/L for γ-tocopherol, and 1.2 μmol/L for δ-tocopherol; dietary γ- or δ-tocopherol, however, decreased serum α-tocopherol levels, and dietary α-tocopherol decreased serum levels of γ-tocopherol. Each dietary tocopherol also increased its corresponding side-chain-degradation metabolites, with concentrations of δ-tocopherol metabolites greater than γ-tocopherol and far greater than α-tocopherol metabolites in serum and tumors. This study is the first in vivo assessment of δ-tocopherol in tumorigenesis and shows that δ-tocopherol is more active than α- or γ-tocopherol in inhibiting tumor growth, possibly through trapping reactive oxygen and nitrogen species and inducing apoptosis; δ-tocopherol metabolites could contribute significantly to these results.

γ-Tocotrienol induces growth arrest through a novel pathway with TGFβ2 in prostate cancer

Regions along the Mediterranean and in southern Asia have lower prostate cancer incidence compared to the rest of the world. It has been hypothesized that one of the potential contributing factors for this low incidence includes a higher intake of tocotrienols. Here we examine the potential of γ-tocotrienol (GT3) to reduce prostate cancer proliferation and focus on elucidating pathways by which GT3 could exert a growth-inhibitory effect on prostate cancer cells. We find that the γ and δ isoforms of tocotrienol are more effective at inhibiting the growth of prostate cancer cell lines (PC-3 and LNCaP) compared with the γ and δ forms of tocopherol. Knockout of PPAR-γ and GT3 treatment show inhibition of prostate cancer cell growth, through a partially PPAR-γ-dependent mechanism. GT3 treatment increases the levels of the 15-lipoxygenase-2 enzyme, which is responsible for the conversion of arachidonic acid to the PPAR-γ-activating ligand 15-S-hydroxyeicosatrienoic acid. In addition, the latent precursor and the mature forms of TGFβ2 are down-regulated after treatment with GT3, with concomitant disruptions in TGFβ receptor I, SMAD-2, p38, and NF-κB signaling.

Vitamin E biosynthesis: functional characterization of the monocot homogentisate geranylgeranyl transferase

The biosynthesis of the tocotrienol and tocopherol forms of vitamin E is initiated by prenylation of homogentisate. Geranylgeranyl diphosphate (GGDP) is the prenyl donor for tocotrienol synthesis, whereas phytyl diphosphate (PDP) is the prenyl donor for tocopherol synthesis. We have previously shown that tocotrienol synthesis is initiated in monocot seeds by homogentisate geranylgeranyl transferase (HGGT). This enzyme is related to homogentisate phytyltransferase (HPT), which catalyzes the prenylation step in tocopherol synthesis. Here we show that monocot HGGT is localized in the plastid and expressed primarily in seed endosperm. Despite the close structural relationship of monocot HGGT and HPT, these enzymes were found to have distinct substrate specificities. Barley (Hordeum vulgare cv. Morex) HGGT expressed in insect cells was six times more active with GGDP than with PDP, whereas the Arabidopsis HPT was nine times more active with PDP than with GGDP. However, only small differences were detected in the apparent Km values of barley HGGT for GGDP and PDP. Consistent with its in vitro substrate properties, barley HGGT generated a mixture of tocotrienols and tocopherols when expressed in the vitamin E-null vte2-1 mutant lacking a functional HPT. Relative levels of tocotrienols and tocopherols produced in vte2-1 differed between organs and growth stages, reflective of the composition of plastidic pools of GGDP and PDP. In addition, HGGT was able to functionally substitute for HPT to rescue vte2-1-associated phenotypes, including reduced seed viability and increased fatty acid oxidation of seed lipids. Overall, we show that monocot HGGT is biochemically distinct from HPT, but can replace HPT in important vitamin E-related physiological processes.

Abstract 961: Higher activity of δ-tocopherol (δ-T) than γ-tocopherol and α-tocopherol in the inhibition of lung cancer H1299 xenograft tumors in mice

Abstract Our previous study showed that γ-TmT (a tocopherol mixture containing 57% γ-T, 24% δ-T, 13% α-T and 1.5% β-T) effectively inhibited colon and lung carcinogenesis as well as the growth of transplanted human lung cancer in mice. This study aims to determine the more active constituents in this mixture in a xenograft model. After injection of human lung cancer H1299 cells into NCr nu/nu nude mice, the mice were maintained on a standard AIN93M diet or diet enriched with α-T, γ-T, δ-T or γ-TmT (each at 0.3% and 0.17%) for 50 days. Dietary δ-T showed the strongest inhibition based on final tumor weight (35.6% and 57.6% reduction from the control by 0.17% and 0.3% δ-T, respectively). Dietary 0.3% γ-T and γ-TmT also showed significant inhibition (37.4% and 46% reduction from control, respectively). However, an inhibitory effect was not observed with dietary α-T group. Consistent with the animal study, the growth of H1299 cells was inhibited by tocopherols with their effectiveness following the order of δ-T > γ-TmT > γ-T, but α-T was not effective. We also found that dietary α-T, γ-T and δ-T treatment respectively increased serum α-T, γ-T and δ-T levels (up to 45, 9.7 and 1.2μM, respectively). However, the serum α-T level was decreased by dietary γ-T and δ-T; for example, at 0.3% they decreased α-T levels by 50% and 42% from the control group, respectively. The results suggest a competition among different forms of tocopherols. Dietary treatment with each form of tocopherol also increased the corresponding side-chain degradation metabolites: carboxyethyl hydroxychromans (CEHC) and carboxymethylbutyl hydroxychromans (CMBHC). With 0.3% α-, γ- and δ-T in the diet, the mean serum levels of α-, γ- and δ-CEHC were 0.08, 0.7 and 3.0μM, respectively; and α-, γ- and δ-CMBHC were 0.14, 0.83 and 4.0μM, respectively. These metabolites retain the intact chromanol ring and, similar to their parent tocopherols, could trap reactive oxygen and nitrogen species. δ-CEHC and δ-CMBHC, which are present at rather high concentrations, may play an important role in inhibiting xenograph and tumor growth. The present results show that δ-T and γ-T effectively inhibited human lung cancer xenograft tumors and the inhibition may be due to the apoptosis-inducing, antioxidative, and reactive nitrogen species-trapping activities of these tocopherols and their metabolites (Supported by NIH grants CA120915, CA122474, and CA133021). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 961.

Vitamin E Forms in Alzheimer's Disease: A Review of Controversial and Clinical Experiences

Vitamin E is a collective term for eight naturally occurring compounds, four tocopherols (alpha-, beta-, gamma-, and delta-) and four tocotrienols (alpha-, beta-, gamma-, and delta-). Although it is the major form of vitamin E in US diets, gamma-tocopherol receives little attention when compared to alpha-tocopherol, which is generally found in supplements and most studied for its effects on progression of cognitive impairment. Many clinical trials had been conducted with vitamin E and neurodegenerative disorders, with controversial results, including a recent study which disproves the benefit of vitamin E for Mild Cognitive Impairment and Alzheimer's Disease. This study examined the alpha-tocopherol supplement instead of gamma–tocopherol. Gamma-tocopherol has been found to be more effective in scavenging free radicals and nitrogen oxygen species that cause inflammation; both of these are components of neurodegenerative disorders. Secondly, the use of alpha-tocopherol supplements significantly reduces serum gamma-tocopherol, and this may have important biological effects. Therefore, any potential health benefits of alpha–tocopherol supplements may be offset by deleterious changes in the bioavailability of other forms of tocopherols and tocotrienols. This might account for the null effects of alpha tocopherol supplementation in Mild Cognitive Impairment and Alzheimer's Disease.

Physicochemical Characteristics of Linseed Oil and Flour

The objective of the study was to determine the chemical composition of a new linseed cultivar Zlocisty, characterized by a light seed coat. In this study, determinations were conducted for contents of: water and volatile substances, protein, fat, dietary fiber, acid detergent fiber (ADF) and neutral detergent fiber (NDF), pectins, starch, saccharides, methyl esters of fatty acids, peroxide number of fat, acidic and iodine values of fat, as well as for the percentage contribution of particular forms of lipids, sterols and tocopherols. An analysis of the chemical composition of linseed oil and flour demonstrated that both of these products may be valuable components of dietary supplements. The chemical composition of linseed oil was determined with special attention paid to bioactive substances from tocopherols, sterols and phospholipids. Based on the assayed chemical composition of flour, it appears that it might constitute a rich source of dietary fiber and zinc. The management of both of these semi-products affords the possibility of waste-free seed processing.

Replacement of α-Tocopherol by β-Tocopherol Enhances Resistance to Photooxidative Stress in a Xanthophyll-Deficient Strain of Chlamydomonas reinhardtii

Tocopherols (vitamin E) comprise a class of lipid-soluble antioxidants synthesized only in plants, algae, and some cyanobacteria. The majority of tocopherols in photosynthetic cells is in the alpha form, which has the highest vitamin E activity in humans, whereas the beta, gamma, and delta forms normally account for a small percentage of total tocopherols. The antioxidant activities of these forms of tocopherol differ depending on the experimental system, and their relative activities in vivo are unclear. In a screen for suppressors of the xanthophyll-deficient npq1 lor1 double mutant of Chlamydomonas reinhardtii, we isolated a vte3 mutant lacking alpha-tocopherol but instead accumulating beta-tocopherol. The vte3 mutant contains a mutation in the homolog of a 2-methyl-6-phytyl-1,4-benzoquinone methyltransferase gene found in plants. The vte3 npq1 lor1 triple mutant with beta-tocopherol survived better under photooxidative stress than did the npq1 lor1 mutant, but the vte3 mutant on its own did not have an obvious phenotype. Following transfer from low light to high light, the triple mutant showed a higher efficiency of photosystem II, a higher level of cell viability, and a lower level of lipid peroxide, a marker for oxidative stress, than did the npq1 lor1 mutant. After high-light transfer, the level of the photosystem II reaction center protein, D1, was also higher in the vte3 npq1 lor1 mutant, but the rate of D1 photodamage was not significantly different from that of the npq1 lor1 mutant. Taken together, these results suggest that the replacement of alpha-tocopherol by beta-tocopherol in a xanthophyll-deficient strain of Chlamydomonas reinhardtii contributes to better survival under conditions of photooxidative stress.

Assessment of variation in antioxidative defense system in salt-treated pea ( Pisum sativum) cultivars and its putative use as salinity tolerance markers

The present work describes whether the changes in the activities of antioxidant enzymes and the levels of some non-enzymatic antioxidants could be used as markers of salt tolerance in nine genetically diverse pea (Pisum sativum) cultivars. All cultivars were exposed to four levels of NaCl i.e., 0, 40, 80 and 120mM in sand culture. Plant fresh biomass, total phenolics, total soluble proteins, hydrogen peroxide (H(2)O(2)), malondialdehyde (MDA), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in leaves while different forms of tocopherols (alpha-, gamma- and Delta-tocopherol) in fresh seed of salt-stressed and non-stressed plants were analyzed. On the basis of percent inhibition in shoot biomass at the highest salt level (120mM) cultivars 2001-35, 2001-55 and Climax were ranked as tolerant (percent inhibition less than 60%), 2001-20, 9800-5 and 9800-10 moderately tolerant (percent inhibition 60-70%), and 2001-40, 9200 and Tere 2 salt sensitive (percent inhibition more than 70%). Salt stress markedly enhanced the activities of SOD and POD, levels of total phenolics and gamma- and Delta-tocopherols, and decreased the total soluble proteins and CAT activity, while the internal levels of H(2)O(2) remained unaffected in all pea cultivars. Although salt-induced oxidative stress occurred in all pea cultivars, the response of salt-tolerant and salt-sensitive cultivars with respect to the generation of enzymatic and non-enzymatic metabolites measured in the present study was not consistent. Of different antioxidant enzymes and metabolites analyzed, only CAT activity was found to be a reliable marker of salt tolerance in the set of pea cultivars examined.

Carotenoid and Tocopherol Composition of Leaves, Buds, and Flowers of Capparis spinosa Grown Wild in Tunisia

High-performance liquid chromatography was used to determine carotenoids (beta-carotene, lutein, neoxanthin, and violaxanthin) and tocopherols of leaves, buds, and flowers of Tunisian Capparis spinosa. This plant shows strong resistance to hard environmental conditions, and it is one of the most commonly found aromatics in the Mediterranean kitchen. In this study, the means of the total carotenoids were 3452.5 +/- 1639.4, 1002 +/- 518.5, and 342.7 +/- 187.9 microg/g fresh weight (FW) in leaves, buds, and flowers, respectively. Lutein accounts for the high content. Violaxanthin provided the lowest portion of the total carotenoids. The principal form of tocopherol detected in leaves was alpha-tocopherol (20.19 +/- 10 mg/100 g FW). In buds and flowers, there were both alpha- (49.12 +/- 17.48 and 28.68 +/- 9.13 mg/100 g FW, respectively) and gamma-tocopherol (48.13 +/- 15.08 and 27.8 +/- 16.01 mg/100 g FW, respectively). The combined content of pro-vitamin A and vitamin E in capers encourages researchers to more explore and find developments for this plant.

Relative Changes in Tocopherols, Isoflavones, Total Phenolic Content, and Antioxidative Activity in Soybean Seeds at Different Reproductive Stages

Immature seeds of soybean are becoming increasingly popular as a snack/vegetable to harness the health benefits of soybean. They are shelled from the immature pods picked from the mother plant at different reproductive stages. Information concerning changes in antioxidant constituents and antioxidant capacity during reproductive phases of soybean seeds is scarce. The aim of the present study was to determine whether immature seeds picked at different reproductive stages differ in tocopherol, isoflavone, total phenolic contents, free radical scavenging activity, and total antioxidative capacity. Seeds shelled from the soybean pods picked at three reproductive stages (R5, R6, and R7) as well as at full maturity were subjected to high-performance liquid chromatography analyses for tocopherol and isoflavone contents. Significantly higher values (P<0.05) were observed for tocopherols and isoflavones in immature seeds picked at late reproductive stages. At the first reproductive stage, that is, R5 stage, delta-tocopherol was the predominant form of tocopherol, whereas in subsequent reproductive stages as well as at complete maturity stage, the gamma-isomer contributed maximum proportion to the total tocopherol content. Genistein was, in general, the major form of isoflavone at all reproductive stages. Reduction in free radical scavenging activity, total antioxidant capacity, and total phenolic content in late-picked seeds concomitant with increased concentration of tocopherol and isoflavone isomers was observed. The results show that bioactive constituents other than isoflavones and tocopherols may decline with the advancement of maturity.

Dietary α‐, β‐, γ‐ and δ‐tocopherols in lung cancer risk

Studies of vitamin E and cancer have focused on the alpha-tocopherol form of the vitamin. However, other forms of vitamin E, in particular gamma-tocopherol may have unique mechanistic characteristics relevant to lung cancer prevention. In an ongoing study of 1,088 incident lung cancer cases and 1,414 healthy matched controls, we studied the associations between 4 tocopherols (alpha-, beta-, gamma-, and delta-tocopherol) in the diet and lung cancer risk. Using multiple logistic regression analysis, the adjusted odds ratios (OR) and 95% confidence intervals (CI) of lung cancer for increasing quartiles of dietary alpha-tocopherol intake were 1.0, 0.63 (0.50-0.79), 0.58 (0.44-0.76) and 0.39 (0.28-0.53), respectively (p-trend < 0.0001). For dietary intake of beta-tocopherol, the OR and 95% CI for all subjects were: 1.0, 0.79 (0.63-0.98), 0.59 (0.45-0.78) and 0.56 (0.42-0.74), respectively (p-trend < 0.0001). Similar results for dietary gamma-tocopherol intake were observed: 1.0, 0.84 (0.67-1.06), 0.76 (0.59-0.97) and 0.56 (0.42-0.75), respectively (p- trend = 0.0002). No significant association between delta-tocopherol intake and lung cancer risk was detected. When the 4 tocopherols were summed as total tocopherol intake, a monotonic risk reduction was also observed. When we entered the other tocopherols in our model, only the association with dietary alpha-tocopherol intake remained significant; i.e., increasing intake of dietary alpha-tocopherol accounted for 34-53% reductions in lung cancer risk. To the best of our knowledge, this is the first report of the independent associations of the 4 forms of dietary tocopherol (alpha-, beta-, gamma- and delta-tocohperol) on lung cancer risk. Given the limitations with case-control studies, these findings need to be confirmed in further investigations.

Genetic possibilities for altering sunflower oil quality to obtain novel oilsThis article is one of a selection of papers published in the special issue Bridging the Gap: Where Progress in Cardiovascular and Neurophysiologic Research Meet.

The sunflower is one of the four most important oilseed crops in the world, and the nutritional quality of its edible oil ranks among the best vegetable oils in cultivation. Typically up to 90% of the fatty acids in conventional sunflower oil are unsaturated, namely oleic (C 18:1, 16%-19%) and linoleic (C 18:2, 68%-72%) fatty acids. Palmitic (C 16:0, 6%), stearic (C 18:0, 5%), and minor amounts of myristic (C 14:0), myristoleic (C 14:1), palmitoleic (C 16:1), arachidic (C 20:0), behenic (C 22:0), and other fatty acids account for the remaining 10%. Advances in modern genetics, most importantly induced mutations, have altered the fatty acid composition of sunflower oil to a significant extent. Treating sunflower seeds with gamma- and X-rays has produced mutants with 25%-30% palmitic acid. Sunflower seed treatment with X-rays has also resulted in mutants having 30% palmitoleic acid, while treatments with mutagenic sodium azide have produced seeds containing 35% stearic acid. The most important mutations have been obtained by treatment with dimethyl sulfate, which produced genotypes with more than 90% oleic acid. Mutants have also been obtained that have a high linoleic acid content (>80%) by treating seeds with X-rays and ethyl methanesulfonate. Of the vitamin E family of compounds, sunflower oil is known to predominantly contain alpha-tocopherol (>90%). Spontaneous mutations controlled by recessive genes have been discovered that significantly alter tocopherol forms and levels. The genes in question are tph(1) (50% alpha- and 50% beta-tocopherol), tph(2) (0%-5% alpha- and 95%-100% gamma-tocopherol), and tph(1)tph(2) (8%-40% alpha-, 0%-25% beta-, 25%-84% gamma-, and 8%-50% delta-tocopherol). The existence of (mutant) genes for increased levels of individual fatty acids and for different forms and levels of tocopherol enables the development of sunflower hybrids with different oil quality. The greatest progress has been made in developing high-oleic hybrids (>90% oleic acid). There has been considerable work done recently on the development of high-oleic hybrids with altered tocopherol levels, the oil of which will have 10-20 times greater oxidative stability than that of conventional sunflower oil. While sunflower breeders work on developing hybrids with altered oil quality, medical scientists in general and nutritionists in particular will determine the parameters for the use of these novel types of oil that can improve human nutrition and be used in the prevention of cardiovascular diseases.

Effects of tocopherols and 2,2′-carboxyethyl hydroxychromans on phorbol-ester-stimulated neutrophils

Tocopherol vitamers [e.g., alpha-, gamma- and delta-tocopherol (α-TOC, γ-TOC and δ-TOC, respectively)] and their water-soluble 2,2′-carboxyethyl hydroxychroman metabolites (e.g., α-, γ- and δ-CEHC) all possess antioxidant properties. As a consequence, and similarly to other natural antioxidants, vitamin E compounds may be useful in preventing inflammatory and oxidative-stress-mediated diseases. In this study, we investigated the concentration-dependent effect of tocopherols and water-soluble metabolites on a key event in oxidative stress, for example, the oxidative burst in neutrophils. It was found that not only α-TOC but also γ-TOC and δ-TOC as well as α-, γ- and δ-CEHC at physiological concentrations inhibit superoxide anion (O 2 •−) production in phorbol-ester-stimulated neutrophils. This effect was mediated by the inhibition of the translocation and activation of protein kinase C (PKC) enzyme, which is the key event in the phorbol-ester signaling. Importantly, CEHCs were stronger inhibitors of PKC as compared with the vitamer precursors, and the gamma forms of both tocopherol and CEHC showed the highest inhibitory activities. Tocopherols, but not CEHCs, directly inhibit the fully activated nicotine–adenine–dinucleotide phosphate (NADPH) oxidase. However, none of the test compounds was able to directly scavenge O 2 •− when tested in a cell-free system. In conclusion, vitamin E compounds can control the neutrophil oxidative burst through the negative modulation of PKC-related signaling and NADPH oxidase activity. As an original finding, we observed that CEHC metabolites might contribute to regulate PKC activity in these cells. These results may have important implications in the anti-inflammatory and antioxidant role of vitamin E compounds.

Molecular and Cellular Activities of Vitamin E Analogues

Natural vitamin E comprises 8 different analogues, the alpha-, beta-, gamma-, and delta-tocopherols and the alpha-, beta-, gamma-, and delta-tocotrienols. However, only alpha-tocopherol is selectively enriched by the liver; the other vitamin E analogues and also excess alpha-tocopherol are converted to several metabolites and eliminated. Recently, a novel phosphorylated form of tocopherol, alpha-tocopheryl phosphate, was shown to occur naturally in animal and human tissues as well as in foods. Several synthetic vitamin E derivatives have been synthesized that are either converted by esterases to the natural form, or exert novel or vitamin E related biological activities. During the last years, specific cellular effects for each individual vitamin E analogue have been described that are the consequence of modulating signal transduction and gene expression. These effects possibly reflect specific interactions of each of the vitamin E analogues with enzymes, structural proteins, lipids and transcription factors. In this review, the different natural vitamin E analogues and synthetic derivatives are compiled in relation to their major molecular and cellular activities.

Functional diversity of tocochromanols in plants

Tocochromanols encompass a group of compounds with vitamin E activity essential for human nutrition. They accumulate in photooxidative organisms, e.g. in some algae and in plants, where they localize to thylakoid membranes and plastoglobules of chloroplasts. Tocochromanols contain a polar chromanol head group with a long isoprenoid side chain. Depending on the nature of the isoprenoid chain, tocopherols (containing a phytyl chain) or tocotrienols (geranylgeranyl chain) can be distinguished in plants. The tocochromanol biosynthetic pathway has been studied in Arabidopsis and Synechocystis in recent years, and the respective mutants and genes were isolated. Mutant characterization revealed that tocopherol protects lipids in photosynthetic membranes and in seeds against oxidative stress. In addition to its antioxidant characteristics, tocopherol was shown be involved in non-antioxidant functions such as primary carbohydrate metabolism. A considerable proportion of tocopherol is synthesized from free phytol suggesting that excess amounts of phytol released from chlorophyll breakdown during stress or senescence might be deposited in the form of tocopherol in chloroplasts.

Cyclodextrin-modified microemulsion electrokinetic chromatography for separation of α-, γ-, δ-tocopherol and α-tocopherol acetate

Different forms of tocopherols, together with tocotrienols, are collectively named as vitamin E, and each possesses different degree of medical, biological and physiochemical significance. The main difficulty of separating different forms of tocopherols lay in their highly structural similarities and hydrophobicities. Microemulsion electrokinetic chromatography (MEEKC), claimed to attain high peak efficiency with great solubilization power, has not previously been applied to the separation of tocopherols. The effects that various parameters, such as buffer system, type and concentration of cyclodextrins, temperature, and sample matrix, have on the separation of tocopherols by MEEKC have been investigated. By using a buffer mixture of 4% (w/w) sodium dodecyl sulfate (SDS), 6.6% (w/w) 1-butanol, 0.8% (w/w) n-octane, 20% (w/w) 2-propanol, 68.6% (w/w) phosphate (25 mM, pH 2.5), and 25 mM heptakis(2,6-di- O-methyl)-β-cyclodextrin (DM-β-CD), the separation of α-, γ-, and δ-tocopherol, α-tocopherol acetate, as well as the antioxidant butylated hydroxytoluene (BHT) at −26 kV, 25 °C was completed within 35 min. The practical potential of the present approach has been further validated by the determination of tocopherols in a vitamin E preparation, with the result of 132.63 (RSD 1.25%), 176.51 (RSD 0.29%), and 64.32 mg (RSD 3.34%) per 500 mg capsule for α-, γ- and δ-tocopherol, respectively.

Tocotrienols: Vitamin E beyond tocopherols

In nature, eight substances have been found to have vitamin E activity: α-, β-, γ- and δ-tocopherol; and α-, β-, γ- and δ-tocotrienol. Yet, of all papers on vitamin E listed in PubMed less than 1% relate to tocotrienols. The abundance of α-tocopherol in the human body and the comparable efficiency of all vitamin E molecules as antioxidants, led biologists to neglect the non-tocopherol vitamin E molecules as topics for basic and clinical research. Recent developments warrant a serious reconsideration of this conventional wisdom. Tocotrienols possess powerful neuroprotective, anti-cancer and cholesterol lowering properties that are often not exhibited by tocopherols. Current developments in vitamin E research clearly indicate that members of the vitamin E family are not redundant with respect to their biological functions. α-Tocotrienol, γ-tocopherol, and δ-tocotrienol have emerged as vitamin E molecules with functions in health and disease that are clearly distinct from that of α-tocopherol. At nanomolar concentration, α-tocotrienol, not α-tocopherol, prevents neurodegeneration. On a concentration basis, this finding represents the most potent of all biological functions exhibited by any natural vitamin E molecule. An expanding body of evidence support that members of the vitamin E family are functionally unique. In recognition of this fact, title claims in manuscripts should be limited to the specific form of vitamin E studied. For example, evidence for toxicity of a specific form of tocopherol in excess may not be used to conclude that high-dosage “vitamin E” supplementation may increase all-cause mortality. Such conclusion incorrectly implies that tocotrienols are toxic as well under conditions where tocotrienols were not even considered. The current state of knowledge warrants strategic investment into the lesser known forms of vitamin E. This will enable prudent selection of the appropriate vitamin E molecule for studies addressing a specific need.

Serum Alpha- and Gamma-Tocopherol Levels in Atopic Mothers and Their Infants Are Correlated

Background: Vitamin E may have immunomodulatory properties beyond its antioxidant function. The objective here was to assess the α- and γ-tocopherol status and its correlation between atopic mothers and their infants. Methods: Mothers with atopic disease were recruited at the end of gestation and their infants were followed up. Serum samples from mothers and infants were collected at the infants’ age of 1 month. Atopic dermatitis was diagnosed during the 1st year of life and skin prick tests were performed at 1 year. Results: Infants’ serum γ- and α-tocopherol to fat ratios were significantly correlated with maternal serum ratios (r = 0.70, p < 0.0001 and r = 0.52, p = 0.004, respectively). In infants the serum α-tocopherol/fat was higher and the γ-tocopherol/fat ratio lower than in mothers. Serum tocopherol levels were not associated with skin prick test reactions or atopic dermatitis in the infants. Conclusions: Maternal tocopherol status determines that of the infant. Different tocopherol forms may have different serum levels and roles in the regulation of inflammatory diseases.

Interpretation of Genotype-by-Environment Interaction for Carotenoid and Tocopherol Content in Broccoli

Genotype-by-environment interaction (G×E) is a fundamental concern in plant breeding since it hinders developing genotypes with wide geographical usefulness. Analysis of variance (ANOVA) has been widely used to interpret G×E, but it does not elucidate the nature and causes of the interaction. Stability analysis provides a summary of the response patterns of genotypes to different growing environments. Two classes of phytochemicals with putative health promoting activity are carotenoids and tocopherols that are relatively abundant in broccoli. Growing clinical and epidemiological evidence suggests that vegetables with enhanced levels of these phytochemicals can reduce the risk of cancer, cardiovascular, and eye diseases. The objective of this study is to have better understanding of the genetic, environmental and G×E interaction effects of these phytochemicals in broccoli to determine the feasibility of the genetic enhancement. The ANOVA and Shukla's stability test were applied to a set of data generated by the HPLC analysis of different carotenoid and tocopherol forms for six broccoli accessions grown over three environments. The ANOVA results show a significant G×E for both phytochemicals that ranged from 22.6% of the total phenotypic variation for beta-carotene to 54.0% for delta-tocopherol while the environmental effects were nonsignificant. The genotypic effects ranged from as low as 1% for alpha-tocopherol to 31.5% and 36.0% for beta-carotene and gamma-tocopherol, respectively. Stability analysis illustrated that the most stable genotype for all phytochemicals is Brigadier. The results suggest that feasibility of the genetic enhancement for major carotenoids and tocopherols. A second experiment that includes a larger set of genotypes and environments was conducted to confirm the results of this study.

Linking tocopherols with cellular signaling in plants

Linking tocopherols with cellular signaling in plants